Conventional capacitor, line and load switches for transmission and distribution voltages include sophisticated mechanical drive systems with latches that drive contactors that are typically housed within sealed containers. The drive systems typically include spring-loaded toggle system and mechanical latches triggered by hand or an electronic control system. Because the drive system is fairly large, this portion of the switch is located outside the sealed container housing the contactor portion of the switch. This necessitates an opening through the sealed container and an associated moving or sliding seal allowing a mechanical connection between the drive system located outside the sealed container and the contactor located inside the container. The seal is often exposed to the weather, subject to wear, and presents a potential point of failure requiring inspection and occasional replacement.
The conventional capacitor switch arrangement also includes a ballast resistor typically located outside the sealed container that is temporarily connected in the circuit as the switch is opened or closed to suppress initial charging and discharging current spikes and transients of the capacitor as the switch is initially opened or closed. Similar current spikes and transients also occur when switching inductive load currents during line and load switching operations. Like the drive mechanism, the ballast resistor is typically located outside the sealed container requiring another opening through the container and associated seal.
The conventional arrangement described above for capacitor, line and load switches operating at transmission and distribution voltages is physically large compared to the sealed container itself, mechanically complex, requires one or more seals through the container, and is correspondingly expensive from acquisition and operation standpoints. There is, therefore, a continuing need for smaller, simpler, more durable, and more economical solution to capacitor, line and load switching.